Magnetic catch



Sept. 7, 1965 M. o. TEl-:TOR

MAGNETIC CATCH Filed July l0, 1963 United States Patent O 3,204,995 MAGNETIC CATCH Macy 0. Teetor, Metaii'e, New Orleans, La., assignor to National Manufacturing Co., Sterling, Ill., a corporation of Illinois Filed July 10, 1963, Ser. No. 294,044 11 Claims. (Cl. 292-2515) This invention relates to magnetic catches, and more particularly to a novel magnetic catch adapted for use on doors or the like.

Various types of magnetic catches have been advanced heretofore for use on doors or other closure members for holding the door in a xed or closed position with respect to a frame member. When catches of this type are utilized to hold large or heavy doors in a closed or open position, a powerful permanent magnet element must be employed. Because the magnetic forces developed 'by such a magnet element are quite large, `the force holding the door in a closed or open position is frequently so great that the door cannot be moved with normal effort. To overcome this disadvantage, magnetic catches of the foregoing type have been developed which make special provision for disrupting the large magnetic forces holding the door in either an open or closed position.

In my prior Patent No. 2,815,235 I have disclosed one type of magnetic catch which overcomes the foregoing force problem by utilizing the inertial force of the door with which the catch is associated to facilitate disruption of the magnetic force holding the magnet and armature units of the catch engaged.

In addition, in my prior Patent No. 2,962,318, I have disclosed and claimed another type of magnetic catch employing a pair of spaced spring members which are effective to exert an inward retracting force on the movi able magnet assembly of the catch to prevent rattling and to cushion the :assembly when the armature and magnet units separate.

As will hereinafter appear, the magnetic catch of the present invention incorporates certain improvements over the constructions disclosed in the aforementioned patents.

Accordingly, it is a general object of the present invention to provide a novel and improved magnetic catch construction.

A more particular object of the invention is to provide a novel magnetic catch employingra one piece housing which can be readily diecast or molded.

A further object of the invention is to provide a novel magnetic catch in which the parts thereof may be readily assembled without machine operations such as riveting or bending of lips.

Still another object of the invention is to provide a novel magnetic catch which employs a rectangular shaped plate-like permanent magnet element which is free of holes and notches. Y

A further object of the invention is to provide a novel magnetic catch which is simple in construction, economical to manufacture, and quiet in operation.

Other objects and advantages of the invention will become apparent from the `following detailed description and accompanying sheets of drawings, in which:

FIG. l is a fragmentary perspective view of a magnetic catch embodying the features of the present invention and showing the magnet and armature units of the catch as they would appear when mounted in the jamb strip of a door frame and in a door;

FIG. 2 is a somewhat enlarged fragmentary sectional View of a portion of the door frame and door of FIG. 1 and showing the magnet and armature units as they would appear when the catch is holding the door in a closed position;

saunas! Patented Sept. 7, 1955 ICC FIG. 3 is an end elevational View on an enlarged scale taken along the line 3-3 of FIG. 1;

FIG. 4 is a sectional View taken along the line 4--4 of FIG. 2;

FIG. 5 is a plan view of the rear side of the magnet unit of the catch;

FIG. 6 is a plan View of the front side of the magnet unit;

FIG. 7 is an enlarged sectional view taken along the line 7-7 of FIG. 4; and

FIG. 8 is a sectional view, similar to FIG. 4, showing an alternate construction of the magnet unit of the present invention, the latter comprising a second embodiment thereof.

In FIGS. 1 and 2, a magnetic catch 10 embodying the features of the present invention is illustrated. The catch 10 comprises a magnet unit 11 and an armature unit or plate 12, the magnet unit 11 in this instance being mounted on a door frame 13, as by screws 14, and the armature plate 12 being mounted on a door 16, as by screws 17. The door frame 13 includes the usual door stop or jamb strip 18 and the latter is cut out or notched, as at I9, to receive the magnet unit 11 therein in the manner illustrated in FIG. l. The armature plate 12 is mounted on the door 16 for coaction with the magnet unit 11 when the door is closed and abuts the jamb 18. It will be understood that the mountings of the magnet and armature units 11 and 12 could be reversed with respect to the door frame 13 and door 16, and that the catch 10 could be mounted at other locations around the door frame 13, such as at the top of the frame.

Referring now to FIGS. 3-7, inclusive, in conjunction with FIGS. l and 2, it Will be seen that the magnet unit 11 comprises a generally rectangular shaped, open-ended housing y2t) having a pair of longitudinally spaced side walls 21 which are connected at the front side, indicated at 22, of the housing 20 by a plate-like Wall 23 (FIG. 6) and at the rear side, indicated at 24, of the housing 20 by a longitudinally extending bar portion 25. The bar portion 25 is disposed adjacent the left or armature engaging end, indicated at 26, of the housing 20. The opposite or right end of the housing 20 is indicated at 27 in FIGS. 4-6. The housing 20 is of non-magnetic material, such as aluminum, brass, or plastic, and is preferably a oriepiece structure formed, for example, by diecasting or molding. In the description of the kmagnet unit 11 which follows, references to directions relative to the length, width and thickness of the housing 2l) will be referred to as longitudinal, lateral and transverse, respectively.

Each side Wall 21 is provided with a pair of laterally spaced bores 28 which extend transversely through the housing 20 and which are adapted to receive the screws 14 for securing the housing to a support, such as the door frame 13, in the manner illustrated in FIG. l.

A generally rectangular shaped permanent magnet assembly 30 is loosely mounted in the housing 20 and is supported therein by the side walls 21, the plate-like front wall 23, and the bar portion 25 at the rear side 24 of the housing. A pair of longitudinally spaced flanges 31 (FIG. 5), disposed adjacent the right end 27 of the housing 20, extend longitudinally inwardly from the side walls 21 and also support the rear side of the'magnet assembly 3l).

The magnet assembly 3i), in the present instance, comprises a rectangular shaped permanent magnet element 436 and a pair of rectangular shaped pole pieces 37 and 38 of somewhat greater width than the magnet element 36. The length of the magnet element 36, and pole pieces 37 and 38, is somewhat less than the spacing between the inner surfaces of the side walls 21. Such relationship permits lateral movement of the magnet assembly 30 in the housing 20 Without binding, and also permits the assembly 30 to cock to a limited extent to accommodate small misalignments between the pole faces, indicated at 39 (FIGS. 3, 4 and 6), of the pole pieces 37 and 3S and the armature plate 12.

The permanent magnet element 36 is preferably of the sintered ceramic type formed from barium and iron oxides and available commercially under the trademark Indox. Such material is particularly well suited for use in a magnetic catch application because of its high coercive force, ease of magnetization, and low cost. The generally rectangular wafer-like configuration of the magnet element 36 is utilized because the magnetic properties of Indox are best utilized when the material is formed to a shape providing a relatively large magnetic area and a relatively short magnetic length. Thus, the magnet element 36 is preferably magnetized along an axis extending transversely of or through the thickness of the wafer. Consequently, the magnet element 316 has a rela tively large cross sectional area and at the same time the pole-to-pole distance or the dimension of the magnet in the direction of its magnetic axis is relatively small.

In order to limit outward movement of the magnet assembly 30, and particularly the pole faces 39 thereof, through the open left end 26 of the housing 20 when the assembly is engaged with the armature plate 12 and the latter is being moved away from the magnet unit 11, such as during opening of the door 16, the side walls 21 are provided with a pair of longitudinally spaced, inwardly extending flanges 42 (FIGS. 4 and 6). The flanges 42 are disposed adjacent the left end 26 of the housing and coact with a pair of shoulders 43 formed by notches at the adjacent corners of the pole pieces 37 and 38 to limit outward movement of the magnet assembly. The inner end edges of the flanges 42 and the longitudinal side edge of the bar portion thus define one of the open ends of the housing 20.

As heretofore mentioned, the magnet assembly is loosely mounted in the housing 20. Such loose mounting permits a limited amount of lateral movement of the magnet assembly 30 in the housing before the shoulders 43 engage the flanges 42. Such movement permits the utilization of the inertial force of the door 16 to assist separation of the armature plate 12 from the magnet assembly 30. However, when the armature plate 12 is engaged with the magnet assembly 30, such loose mounting may result in rattling in the magnet unit 11 or of the door 16 against the jamb strip 18. To minimize this possibility, the magnet unit 11 includes an elongated resilient member in the form of a leaf spring 46 which is centrally connected to the magnet assembly 30 at the right side thereof and which urges the assembly inwardly of the housing 20 or toward the right end 27 thereof.

The leaf spring 46 is of a non-magnetic material, such as brass, and has a width substantially equal to the thickness of the magnet element 36 `and a length somewhat greater than that of the magnet assembly 30. The ends of the spring 46 extend into a pair of longitudinally spaced transverselyextending slots or grooves 47 formed in the inner surfaces of the side walls 21 adjacent the right end 27 of the housing 20. As will be apparent from FIGS. 5 and 6, the slots 47 extend transversely across the housing 20 with their right ends opening in the front side 22 of the housing. The left ends of the slots 47 are closed by the flanges 31 (FIG. 5). The spring 46 is held in engagement with the magnet asl sembly 30 by a pair of transversely spaced inwardly di- CTI 12 is broken, an elongated flexible member in the form of another leaf spring 52 is mounted in the slots 47 outwardly of the spring 46 and on the opposite side of the lugs 48. The spring 52 is also of non-magnetic material, such as brass, and has a length substantially equal to that of the spring 46 but a width substantially equal to the thickness of the magnet assembly 30, i.e. the combined transverse thicknesses of the magnet element 36 and plates 37 and 38. The spring 52, While being of the same thickness as the spring 46, is thus substantially stiffer than the latter. Such stiffness facilitates cushioning of the inwardly retracting magnet assembly 30 when the magnetic contact with the armature plate 12 is broken.

To assure retention of the spring 52 in the slots 47 and closing of the right open end of the housing 2f), the right longitudinal edge, indicated at 49, of the front wall 23 is of convex shape so that a portion thereof projects laterally outwardly beyond the slots 47. The spring 52 must thus be deflected or flexed around the convex edge 49 before the ends thereof can be shifted edgewise into the slots 47. When the ends of the spring 52 are fully received in the slots 47, the projecting convex portion 49 of the Wall 23 and the flanges 31 form retaining abutments coacting with the opposite longitudinal edges of the spring 52.

Thus, one exemplary assembly procedure of the parts of the magnet unit 11 is as follows. Initially the permanent magnet assembly 30 is disassembled and the plate 37 and permanent magnet element 36 are shifted into the interior of the housing 20 through the open right end 27 thereof with the plate 37 engaging the inner surface of front wall 23 and the lug 48 thereof extending transversely inwardly. Thereafter, the leaf spring 46 is mounted in the housing by inserting the ends of the spring in the slots 47 and flexing the central portion thereof around the convex right edge 49 of the front wall 23. The spring 46 is then shifted edgewise in the slots 47 until the central portion of the spring clears the convex edge 49.

Once the spring 46 has passed the convex edge 49, it may be readily manipulated to its normal operating position between the lug 48 of the plate 37 and the adjacent longitudinal end face of the permanent magnet element 36. With the parts thus arranged, the plate 38 of the magnet assembly 30 may be shifted into the housing 20 between the exposed transverse side face of the magnet element 36 and the inner surfaces of the bar portion 2S and flanges 31. The plate 38 is of course arranged so that its lug 48 extends transversely inwardly for engaging the leaf spring 46. To complete the assembly, the spring 52 is mounted in the housing 20 in the same manner as the spring 46 so that the ends of the spring 52 are received in the slots 47 and the former closes the right open end of the housing. When the spring 52 occupies its aforementioned position closing the .right end 27 of the housing 20, it is retained at its ends in the slots 47 and along its longitudinal edges by the adjacent inner surfaces of the front wall 23 and flanges 31. In addition, the lateral end faces of the lugs 48 will centrally engage the spring 52 in the manner illustrated in FIG. 5. A pair of longitudinally spaced laterally extending cutouts or notches 53 are provided in the front wall 23 adjacent the slots 47 to provide access to the slots 47 and the interior of the housing 20. When thus assembled, the magnet unit 11 is ready for installation at a desired location.

In operation, assuming that the magnet unit 11 and armature plate 12 have been respectively mounted on the door frame 13 and door 16, in the manner illustrated in FIG. 1, and that the door is open, the magnet assembly 30 will occupy the approximate position illustrated in FIG. 6. Thus, the pole faces 39 will be disposed somewhat inwardly of the left end 26 of the housing 20 due to the retracting force of the spring 46. As the door 16 is closed and the armature plate 12 moves into close proximity to the magnet unit 11, the magnet assembly 30 will shift outwardly in the housing 20 toward the armature and the pole faces 39 Will engage the arma` ture plate 12. Such movement of the magnet assembly 30 is resisted with increasing force due to the action of the spring 46.

After magnetic contact has been established between the magnet assembly 30 and armature plate 12, the latter Will be held in engagement with the left end 26 of the housing 20 because of the inward retracting force of the spring 46 acting on the magnet assembly 30 through the lugs 48. The parts of the catch will thus assume the approximate position illustrated in FIG. 4. When so positioned, the shoulders 43 on the pole pieces 37 and 38 are spaced laterally inwardly from the flanges 42 of the housing 20.

When force is exerted on the door 16 to open it, the magnet assembly 30 will shift toward the left end 26 of the housing with the door and armature plate 12 until the shoulders 43 contact the flanges 42. This slight amount of free movement of the magnet assembly 30 permits the door 16 to acquire a small inertial force, which is utilized when the shoulders 43 contact the flanges 42, to assist in the disruption of the magnetic contact between the pole faces 39 and the armature unit 12. When the magnetic contact is broken, the spring 46, which has bowed inwardly because of the movement of the magnet assembly 30, serves to retract the latter into the housing Ztl. When the inwardly retracting magnet assembly 30 reaches the approximate position illustrated in FIG. 5, the lugs 48 engage the heavier leaf spring 52 which bows outwardly under the impact. The magnet assembly 3i) is thus cushioned and excessive noise is avoided.

It will thus be appreciated that by positioning both springs 46 and 52 at one side of the magnet assembly 30 a simplified structural arrangement is achieved. In addition, a simplified housing structure is provided in that a single pair of slots 47 serves to retain both springs 46 and 52.

Referring now to FIG. 8, another magnetic catch 50 is illustrated, the latter comprising a second embodiment of the invention. Like reference numerals have been used to identify the parts of the catch 50 identical with those of the catch 10.

As will be apparent from FIG. 8, the magnetic catch 50 differs from the catch 1t) by the provision of a single elongated iiexible member 51 seated in the slots 47, instead of the pair of springs 46 and 52. The member 51 is also of non-magnetic material and preferably comprises a strip of relatively stiff but bendable plastic. The strip 51 is of substantially the same length and width as the spring 52 in the first-described embodiment and is mounted in the slots 47 in the same manner as the spring 52. That is, the central portion of the strip 51 must be flexed around the convex edge 49 of front wall 23 (not shown in FIG. 8) in order to permit the ends thereof to move edgewise and fully seat in the slots 47. The plastic strip 51 thus serves to close the open right en`d of the housing 20 of the catch 50 in the same manner as the spring 52 of the previous embodiment, but because the strip 51 is of a plastic material, a more economical construction is provided.

The magnetic catch 50 differs from the previous embodiment in one other respect, namely, no connection is contemplated between the magnet assembly, indicated at 55, and the strip 51. Consequently, the lugs 48 of the previous embodiment are unnecessary and have been omitted from the pole pieces 0f the magnet assembly 55. With no lugs to connect the magnet assembly 55 to the strip 51, the former is freely shiftable in the housing 20 and may cock to accommodate slight misalignments between the armature plate 12 and pole faces of the magnet assembly 55. Thus, when the armature plate 12 is engaged with the pole faces of the magnet assembly 55, the plate 12 may also engage with the left end 26 of the housing 20 or a slight clearance may be present. The

loose t of the magnet assembly 55 also permits the utilization of the inertial force of the door 16 to assist in breaking the magnetic contact between the armature plate and magnet unit, as in the previous embodiment.

As an incident to the elimination of any connection between the strip 51 and magnet assembly 55, assembly of the magnet unit, indicated at 56, of the catch 50 is a simple procedure. Thus, the magnet element 36 and pole pieces of the assembly 55 are arranged in sandwiched relation before the assembly is mounted in the housing and the complete assembly is thereafter shifted into the housing through the open end 27 of the housing 20. Thereafter, the strip 51 is inserted in the slots 47 in the manner of the leaf spring 52 of the previous embodiment. The magnet unit 56 is then ready for installation.

While only two embodiments of the invention have been herein illustrated and described, it will be understood that modifications and variations may be effected without departing from the scope of the invention as set forth in the appended claims.

I claim:

1. In a magnetic catch, a magnet unit mountable on one of a pair of door and frame members for coaction with an armature mounted on the other of said members, said magnet unit comprising a generally rectangular, non-magnetic housing including a pair of longitudinally spaced side walls and laterally spaced open end portions, a generally rectangular permanent magnet assembly movably disposed in said housing, said permanent magnet assembly having pole portions adapted to project from said housing through one open end thereof for Contact with said armature, means limiting outward movement of said magnet assembly through 4said one open end, said longitudinally spaced side walls having opposed transversely extending slots formed therein adjacent the other open end of said housing, and an elon gated member mounted in said housing and closing said other open end thereof, the ends of said elongated member being received in said respective slots, said elongated member being effective to retain said magnet unit in said housing.

2. The combination of claim 1 further characterized in that said housing includes a plate-like front wall connecting said side walls at the front sides thereof, and the ends of said transverse slots in said side walls are open and unobstructed for receiving the longitudinal ends of said elongated member.

3. The combination of claim 2 further characterized in that said housing includes a pair of longitudinally spaced flanges extending longitudinally inwardly from said side walls at the rear side of said housing, said iiaps closing the opposite ends of said slots and providing a lsupport for said magnet assembly and the ends of said elongated member.

4. The combination of claim 3 further characterized in that said housing includes a longitudinally extending bar portion connecting said side walls at the rear portions thereof adjacent said one open end, said bar portion supporting said magnet assembly adjacent its pole portions.

5. The combination of claim 2 further characterized in that said elongated member is of flexible material, and the lateral side edge of said plate-like front wall adjacent said slots projects laterally outwardly of said slots, whereby said elongated member must be flexed around said projecting side edge of said front wall for effecting engagement thereof in said slots.

6. The combination of claim 2 further characterized in that said elongated member has a width substantially equal to the thickness of said permanent magnet assembly.

7. In a magnetic catch, a magnet unit comprising a generally rectangular non-magnetic housing including spaced front and rear face portions, spaced side walls, and spaced open end portions, a permanent magnet assembly movably disposed in said housing and having pole portions adapted to project through one of said open end portions for engaging a cooperating armature, said housing and said magnet assembly having coacting portions for limiting movement of the magnet assembly through said one open end portion, means at said side walls defining a pair of opposed recesses extending transversely between said face portions adjacent the opposite open end portion of said housing, an elongated deectable closure strip extending along said opposite open end portion of said housing with the ends of said strip loosely and detachably received in said recesses for retaining Isaid magnet assembly in said housing, and spaced abutments on said housing at said face portions overlying the opposite longitudinal edges of said strip for normally retaining said strip in assembled relation with said housing, said recesses being unobstructed and accessible from at least one of said .face portions of said housing for edgewise insertion or removal of the ends of said strip relative to said recesses after said strip has ybeen deflected to clear the abutment at said one face portion.

8. In a magnetic catch for holding a closure member adjacent a frame member, a magnet unit mountable on one of said members for coaction with an armature unit mounted on the other of said members, said magnet unit comprising a generally rectangular openended housing of non-magnetic material, said housing including spaced side walls and a connecting front wall, a generally rectangular-shaped permanent magnet assembly loosely and movably disposed in said housing, said magnet assembly including pole portions adapted to project outwardly of said housing through one open end thereof for engaging said armature unit, means limiting outward movement of said magnet assembly through said one open end of said housing, and a pair of elongated spring members mounted in said housing and disposed adjacent the side of said magnet assembly opposite from the pole portions thereof and adjacent said other open end, one of said spring members being connected to said magnet assembly for resiliently urging the latter inwardly of said housing, the other of said spring members spanning said other open end of said housing and serving as a resilient cushion for the inwardly retracting magnet assembly upon disengagement thereof from said armature unit.

9. The combination of claim 8 further characterized in that said magnet assembly comprises a plate-like magnet element and a pair of plate-like pole pieces disposed at opposite sides of said magnet element, said pole pieces having inturned lug means engaging said one spring member and providing a connection therebetween.

16. The combination of claim 9 further characterized in that said one spring member has a width substantially equal to the thickness of said magnet element, and said other spring member has a width substantially equal to the thickness of said magnet assembly, whereby said other spring member closes the other open end of said housing when mounted therein.

11. The combination of claim 16 further characterized in that said lug means is located substantially centrally of said pole pieces, whereby a portion of said one spring member nests between said pole pieces.

References Cited by the Examiner UNITED STATES PATENTS 2,770,759 11/,56 Ahlgren 292-2515 X 2,962,318 ll/60 Teetor 292-2515 M. HENSON WOOD, J R., Primary Examiner.

UNITED STATES `PATENT OFFICE CERTIFICATE 0F CORRECTION Patent No. 3,204,995 September 7, 1965 Macy O Teetor It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 6, line 52, for "flaps" read Y- flanges Signed and sealed this 26th day of July 1966e (SEAL) Attest:

ERNEST W. SWIDER Attesting Officer EDWARD I. BRENNER Commissioner of Patents 

1. IN A MAGNETIC CATCH, A MAGNET UNIT MOUNTABLE ON ONE OF A PAIR OF DOOR AND FRAME MEMBERS FOR COACTION WITH AN ARMATURE MOUNTED ON THE OTHER OF SAID MEMBERS, SAID MAGNET UNIT COMPRISING A GENERALLY RECTANGULAR, NON-MAGNETIC HOUSING INCLUDING A PAIR OF LONGITUDINALLY SPACED SIDE WALLS AND LATERALLY SPACED OPEN END PORTIONS, A GENERALLY RECTANGULAR PERMANENT MAGNET ASSEMBLY MOVABLY DISPOSED IN SAID HOUSING, SAID PERMANENT MAGNET ASSEMBLY HAVING POLE PORTIONS ADAPTE TO PROJECT FROM SAID HOUSING THROUGH ONE OPEN END THEREOF FOR CONTACT WITH SAID ARMATURE, MEANS LIMITING OUTWARD MOVEMENT OF SAID MAGNET ASSEMBLY THROUGH SAID ONE OPEN END, SAID LONGITUDINALLY SPACED SIDE WALLS HAVING OPPOSED TRANSVERSELY EXTENDING SLOTS FORMED THEREIN ADJACENT THE OTHER OPEN END OF SAID HOUSING, AND AN ELONGATED MEMBER MOUNTED IN SAID HOUSING AND CLOSING SAID OTHER OPEN END THEREOF, THE ENDS OF SAID ELONGATED MEMBER BEING RECEIVED IN SAID RESPECTIVE SLOTS, SAID ELONGATED MEMBER BEING EFFECTIVE TO RETAIN SAID MAGNET UNIT IN SAID HOUSING. 